In trend of rapidly developing of the computer and semiconductor technology, computer devices such as notebooks and tablet computers are miniaturized. A digital camera, a smart mobile phone, a digital television, and a satellite navigation device, which are all installed with a processor, are also called as computer devices because they are all allocated with their CPUs, the memory, and the I/Os. In spite that the operation speed of these computer devices, which have higher transistor density than before, is faster, it also causes the increase of power consumption and heat generation. It thus leads a higher operation temperature for the computer device and may cause the hardware inside the computer device burned down.
Therefore, it is an important issue to reduce the operation temperature of the computer device in order to prevent it from being shut down.
In the known art, an underlaying device is used for being laid under a computer device so as to improve the air circulation under the computer device in order to release the heat thereof.